(1) Field of the Invention
The present invention relates to a thermoplastic resin composition having excellent impact resistance, heat resistance, chemical resistance, moldability, dimensional stability and appearance of molded articles made therefrom. This composition of the present case can be widely utilized as materials for industrial parts, electrical and electronic machine parts, automobile parts and the like.
(2) Description of the Prior Art
Polyamides, polyphenylene ethers and polycarbonates are called the so-called engineering plastics. These compounds are believed to have mechanical properties, heat resistance, chemical resistance and the like, and they are used in many fields.
In recent years, with regard to the engineering plastics, new additional functions are demanded, and various attempts have been made. One of them is a composition comprising a combination of plural engineering plastics, and this composition has features of the respective plastics and is known as a polymer alloy.
For example, an alloy of a polyamide and a polyphenylene ether, and an alloy of a polyamide and a polycarbonate are known.
The polyamide is excellent in moldability and chemical resistance, but it has hygroscopicity and poor in dimensional stability and impact strength. For the purpose of solving the problem, a method has been suggested in which a polyphenylene ether is mixed with the polyamide. According to a different standpoint, this mixture also intends to improve moldability and solvent resistance which are drawbacks of the polyphenylene ether. However, these two resins are difficult to disperse into each other, and thus some methods for facilitating the dispersion are disclosed in, for example, Japanese Patent Unexamined Publication Nos. 56-16525, 56-49753, 56-47432, 57-36150 and 56-26913. Particularly in Japanese Patent Unexamined Publication Nos. 62-27456, 62-129342, 62-129349 and 62-129351, there are described examples using an epoxy group-containing monomer and a styrene copolymer or an o-olefin copolymer modified with an epoxy group-containing compound in order to improve compatibility.
However, in the ethylene copolymer having the epoxy group, the affinity for the polyamide is good but the affinity for the polyphenylene ether is poor, and for this reason, the improvement of the impact resistance is not sufficient.
When the polycarbonate is mixed with the polyamide to obtain sufficient compatibility, the impact strength of the polyamide resin can be heightened, and the solvent resistance and moldability of the polycarbonate can be effectively improved. Examples in which these two resins are mixed with each other are scarcely present, and any attempt has not been made to improve the compatibility.